Dart Big-M Block Machined Upgrade - Scratching The Surface

The Dart Big-M Block Goes Under The Knife

Anybody who regularly wields a wrench can slam a motor together practically blindfolded. That's the easy part.

If you really think about it, most of the labor is tied up in piecing together the rotating assembly, adding the cylinder heads, and topping it off with the manifold. But if you took a step back and started from scratch, where would you begin? Sure, for the most part our favorite manufacturers are spot-on with their machine work when it comes to engine blocks. However, we're looking to make big power and aren't willing to take any unnecessary chances. When you are in the midst of creating huge reliable strength, why take shortcuts? If you take into account the time and energy, not to mention the cash, that you are willing to throw into your race program, it seems only necessary to have the block machined properly to fit the exact specifications for your application.

This month we left the block in the hands of QMP Racing of Chatsworth, California. Choosing a competent machine/race shop is critical, and over the years we've built good relationships with these race wizards. They've got the know-how to get things done, and they back it up by sponsoring a number of race cars, including a '73 Camaro that recently took a PSCA drag radial championship and an NHRA Division 7 GTO race program. At QMP, expert machinists Mike Consolo and Brad Lagman checked every critical measurements and made sure our tolerances were dead-on. Their combined knowledge was only one reason we chose their shop. They not only facilitate fellow racers with their builds but also utilize an emerging trend and rely on their top-notch CNC machining program, which is where our Dart block was headed. And considering the big plans we have for this Dart block--a monster centrifugal supercharger system--it was vital that we get the job done right first time.

We decided on going for all the beans, pulling out all the stops and getting the block precision-machined with an automated process for much of the work. Our Dart block was delivered to us with a 9.800-inch deck, 4.840-inch bore spacing, and 0.842-inch lifter bores and went through the ringer getting align-honed, decked, bored, lifter-trued, resized lifter bores, and lastly bore-honed with a torque plate. While race shops vary in labor time and prices, we were in and out of the machine shop in a matter of days and spent $1,100 to get the job done. It may seem like a lot, but it's paid insurance and well worth the dough. Plus, when the motor gets put together we won't be running into any problematic issues like the lifters not fitting in the bushings or not having enough clearance for the main bearings once the crankshaft is in. Whether you're into the racing scene or building a boulevard cruiser, any time backpeddling can put a strain on your program.

If you have never seen a block fully machined, it's a sight to behold. Follow along as we take you into QMP's race facility and show you how to get the job done. We show the ins and outs of the machining process, get the scoop on what to look for, and let you know you can expect to pay.